Class: java.io.InputStreamReader

  • public class InputStreamReader
  • extends Reader
An InputStreamReader is a bridge from byte streams to character streams: It reads bytes and decodes them into characters using a specified charset. The charset that it uses may be specified by name or may be given explicitly, or the platform's default charset may be accepted.

Each invocation of one of an InputStreamReader's read() methods may cause one or more bytes to be read from the underlying byte-input stream. To enable the efficient conversion of bytes to characters, more bytes may be read ahead from the underlying stream than are necessary to satisfy the current read operation.

For top efficiency, consider wrapping an InputStreamReader within a BufferedReader. For example: 

 BufferedReader in
   = new BufferedReader(new InputStreamReader(System.in));
Authors:
@author Mark Reinhold
See:
@see java.io.BufferedReader
@see java.io.InputStream
@see java.nio.charset.Charset
Since:
@since JDK1.1

Inheritance

Superclass tree: Implements:

Methods

  • InputStreamReadertop

    public InputStreamReader(InputStream in)
    Creates an InputStreamReader that uses the default charset.
    Parameters:
    @param in An InputStream
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  • InputStreamReadertop

    public InputStreamReader(InputStream in, String charsetName) throws UnsupportedEncodingException
    Creates an InputStreamReader that uses the named charset.
    Parameters:
    @param in An InputStream
    @param charsetName The name of a supported charset
    Exceptions:
    @exception UnsupportedEncodingException If the named charset is not supported
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  • InputStreamReadertop

    public InputStreamReader(InputStream in, Charset cs)
    Creates an InputStreamReader that uses the given charset.
    Parameters:
    @param in An InputStream
    @param cs A charset
    Since:
    @since 1.4
    Misc:
    @spec JSR-51
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  • InputStreamReadertop

    public InputStreamReader(InputStream in, CharsetDecoder dec)
    Creates an InputStreamReader that uses the given charset decoder.
    Parameters:
    @param in An InputStream
    @param dec A charset decoder
    Since:
    @since 1.4
    Misc:
    @spec JSR-51
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  • closetop

    public void close() throws IOException
    Closes this stream and releases any system resources associated with it. If the stream is already closed then invoking this method has no effect.
    Exceptions:
    @throws IOException if an I/O error occurs
    Specified by:
    close from Closeable
    Override hierarchy:
    close from Reader
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  • getEncodingtop

    public String getEncoding()
    Returns the name of the character encoding being used by this stream.

    If the encoding has an historical name then that name is returned; otherwise the encoding's canonical name is returned.

    If this instance was created with the java.io.InputStreamReader.InputStreamReader(java.io.InputStream, java.lang.String) constructor then the returned name, being unique for the encoding, may differ from the name passed to the constructor. This method will return null if the stream has been closed.

    Return:
    @return The historical name of this encoding, or null if the stream has been closed
    See:
    @see java.nio.charset.Charset
    Misc:
    @revised 1.4
    @spec JSR-51
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  • readtop

    public int read() throws IOException
    Reads a single character.
    Return:
    @return The character read, or -1 if the end of the stream has been reached
    Exceptions:
    @exception IOException If an I/O error occurs
    Override hierarchy:
    read from Reader
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  • readtop

    public int read(char[] cbuf, int offset, int length) throws IOException
    Reads characters into a portion of an array.
    Parameters:
    @param cbuf Destination buffer
    @param offset Offset at which to start storing characters
    @param length Maximum number of characters to read
    Return:
    @return The number of characters read, or -1 if the end of the stream has been reached
    Exceptions:
    @exception IOException If an I/O error occurs
    Override hierarchy:
    read from Reader
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  • readytop

    public boolean ready() throws IOException
    Tells whether this stream is ready to be read. An InputStreamReader is ready if its input buffer is not empty, or if bytes are available to be read from the underlying byte stream.
    Return:
    @return True if the next read() is guaranteed not to block for input, false otherwise. Note that returning false does not guarantee that the next read will block.
    Exceptions:
    @exception IOException If an I/O error occurs
    Override hierarchy:
    ready from Reader
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